U.S. patent number 7,288,139 [Application Number 11/470,293] was granted by the patent office on 2007-10-30 for three-phase cyclonic fluid separator with a debris trap.
This patent grant is currently assigned to Eaton Corporation. Invention is credited to Stephen Showalter.
United States Patent |
7,288,139 |
Showalter |
October 30, 2007 |
Three-phase cyclonic fluid separator with a debris trap
Abstract
An apparatus separates liquid, gas and solid components of a
mixture in a fluid system. An inlet for receiving the mixture opens
into a separation chamber tangentially with a cylindrical side wall
and a gas outlet has an opening in a first end wall adjacent the
inlet to allow gas to exit the separator. A fluid outlet is located
in an opposing second end wall. A debris passage extends through
the cylindrical side wall and oriented so that the radial velocity
of the particles within the separation chamber directs the
particles through the debris passage. The debris passage leads to a
particle collection chamber in which the particles accumulate.
Unlike prior separators that relied on the tangential velocity of
the particles, the present apparatus utilizes the greater radial
velocity to drive the particles from the separation chamber into
the particle collection chamber.
Inventors: |
Showalter; Stephen (Milmont
Park, PA) |
Assignee: |
Eaton Corporation (Cleveland,
OH)
|
Family
ID: |
38623283 |
Appl.
No.: |
11/470,293 |
Filed: |
September 6, 2006 |
Current U.S.
Class: |
96/1; 96/209;
210/223; 210/167.03 |
Current CPC
Class: |
B01D
21/30 (20130101); B01D 21/267 (20130101); B01D
21/245 (20130101); B01D 21/26 (20130101); B04C
5/14 (20130101); B04C 5/185 (20130101); B04C
9/00 (20130101); B01D 21/2494 (20130101); B01D
21/2411 (20130101); B01D 21/0006 (20130101); B04C
11/00 (20130101); B03C 1/286 (20130101); B01D
21/0009 (20130101); B03C 2201/28 (20130101); B03C
2201/24 (20130101); B01D 2221/08 (20130101); B03C
2201/18 (20130101) |
Current International
Class: |
B01D
19/00 (20060101) |
Field of
Search: |
;95/28,261
;96/1,209,210,211,212 ;210/167.03,167.02,223,695,788,512.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Smith; Duane
Assistant Examiner: Theisen; Douglas J
Attorney, Agent or Firm: Uthoff, Jr.; Loren H.
Claims
The invention claimed is:
1. An apparatus for separating liquid and particles from a mixture,
said apparatus comprising: a separation chamber having a
cylindrical wall extending between a first end and a second end and
about a longitudinal axis; an inlet, for receiving the mixture,
opens into the separation chamber substantially tangential to the
cylindrical wall; a gas outlet in the first end of the separation
chamber through which gas separated from the mixture exits; a fluid
outlet in the second end of the separation chamber through which
liquid flows from the separation chamber; a debris passage
extending through the cylindrical wall and oriented wherein a
radial velocity of the particles within the separation chamber
directs the particles through the debris passage; and a particle
collection chamber into which the debris passage communicates to
receive the particles.
2. The apparatus as recited in claim 1 wherein the debris passage
extends along a radial line projecting from the longitudinal axis
of the cylindrical wall.
3. The apparatus as recited in claim 1 further comprising an
annular wall projecting into the separation chamber from the second
end and forming a collection region between the annular wall and
the cylindrical wall, wherein the debris passage opens into the
collection region.
4. The apparatus as recited in claim 1 wherein the particle
collection chamber extends from the debris passage parallel to the
longitudinal axis.
5. The apparatus as recited in claim 4 wherein the particle
collection chamber includes an external opening through which
collected debris is extracted from the apparatus, and a closure for
the external opening.
6. The apparatus as recited in claim 1 further comprising a
magnetic probe extending into the particle collection chamber for
gathering metal particles in the debris.
7. The apparatus as recited in claim 6 wherein the magnetic probe
produces an electrical signal indicating an amount of metal
particles that has been gathered.
8. The apparatus as recited in claim 1 further comprising a sensor
that produces an electrical signal indicating an amount of metallic
and non-metallic debris in the particle collection chamber.
9. An apparatus for separating liquid and particles from a mixture,
said apparatus comprising a housing that comprises: a separation
chamber having a first end and a second end with a cylindrical wall
extending there between centered about a first longitudinal axis;
an inlet, for receiving the mixture, opens into the separation
chamber in an orientation which directs the mixture to flow in a
vortex; a fluid outlet in the second end of the separation chamber
through which liquid separated from the mixture flows; a debris
passage extending through with the cylindrical wall along a second
longitudinal axis projecting radially from the first longitudinal
axis; an annular wall projecting into the separation chamber from
the second end and forming a collection region between the annular
wall and the cylindrical wall, wherein the debris passage opens
into the collection region; and a particle collection chamber into
which the debris passage communicates.
10. The apparatus as recited in claim 9 further comprising a gas
outlet in the first end of the separation chamber through which gas
separated from the mixture exits.
11. The apparatus as recited in claim 9 wherein the particle
collection chamber extends from the debris passage parallel to the
first longitudinal axis and away from the first end of the
separation chamber toward a collection end.
12. The apparatus as recited in claim 11 wherein the particle
collection chamber includes an external opening at the collection
end, and a closure for the external opening.
13. The apparatus as recited in claim 9 further comprising a
magnetic probe extending into the particle collection chamber for
gathering metal particles.
14. The apparatus as recited in claim 13 wherein the magnetic probe
produces an electrical signal indicating an amount of metal
particles that has been gathered.
15. The apparatus as recited in claim 9 further comprising a sensor
that produces an electrical signal indicating an amount of debris
in the particle collection chamber.
16. An apparatus for separating liquid, gas, and particles from a
mixture, said apparatus comprising: a separation chamber having a
cylindrical wall extending between a first end and a second end and
about a longitudinal axis; an inlet, for receiving the mixture,
opens into the separation chamber proximate to the first end and
tangentially to the cylindrical wall; a gas outlet at the first end
of the separation chamber through which gas separated from the
mixture exits; a fluid outlet in the second end of the separation
chamber through which liquid flows from the separation chamber; a
debris passage extending through the cylindrical wall and oriented
wherein a radial velocity of the particles within the separation
chamber directs the particles through the debris passage; and a
particle collection chamber into which the debris passage
communicates and extending from the debris passage parallel to the
longitudinal axis and away from the first end of the separation
chamber.
17. The apparatus as recited in claim 16 further comprising a
magnetic probe extending into the particle collection chamber for
gathering metal particles.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to devices for separating debris
particles and gas from fluids in machinery, such as lubricants in
an engine; and more particularly to such devices that perform the
separation by creating a fluid vortex.
2. Description of the Related Art
Modern turbine engines, such as those used in aircraft, are
lubricated by oil supplied to moving engine components by a pump
that draws the oil from a reservoir. The oil flows from those
components into sumps within the engine from which scavenger pumps
force the fluid back to the reservoir. In the course of flowing
through the engine, the oil often picks up metal and non-metal
debris particles and also becomes aerated due to a turbulent flow.
Therefore, it is common practice for this mixture to pass through
an apparatus that separates the particles and entrained gas from
the lubricating oil prior to entering the reservoir.
Such separation has conventionally been performed by a three-phase
cyclonic separator, such as the one described in U.S. Pat. No.
6,348,087. With reference to FIG. 1, this type of separator
receives the fluid mixture from the engine via an inlet passage 100
that is tangentially aligned with the curvature of the inner wall
102 of a cylindrical chamber 106. This alignment causes the fluid
to travel in a vortex 108 downward into an annular debris
collection area 110. The centrifugal force of the vortex drives the
heavier debris particles outward and downward against the
cylindrical inner wall 102 and into the debris collection area
while the fluid flowed through a centrally located outlet 104. The
tangential velocity of the circular flow drives the debris
particles into a linear exit passage 112 that extends tangentially
from the curved surface of the cylindrical inner wall 102 in the
debris collection area. A magnetic particle collector 114 was
located at the remote end of the exit passage to retain metal
particles. The particles must travel some distance along that exit
passage 112 before reaching a magnetic particle collector 114.
Therefore upon entering the exit passage, the particles were
required to have enough momentum to reach the magnetic particle
collector. Small particles often did not possess sufficient
momentum and thus were not retained by the collector.
Specifically, upon entering the exit passage, the particle was out
of the rotational force field of the vortex. The primary forces
counteracting the particle motion were gravity and drag forces. The
drag force F.sub.d is given by the expression:
.times..rho..times..times. ##EQU00001## where C.sub.d is the drag
coefficient, .rho. is the transport fluid density, A is the
projected area of the particle in the direction of flow, and V is
the particle velocity which is assumed to be equal to the fluid
velocity.
The settling velocity V.sub.S of the particle follows Stokes law
and is defined by the equation:
.function..rho..rho..times..times. ##EQU00002## in which g is the
earth gravitational force, d.sub.p is the particle's primary
dimension, .rho..sub.p is the particle's density, .rho..sub.f is
the density of the transport fluid, and .mu. is the fluid
viscosity.
The drag force acts against the particle's momentum, while the
force of gravity moves the particle normal to its intended
trajectory. The attractive force of the magnetic collector is not
apparent until the particle is relatively close due to the design
of the pole piece that confines the flux lines to a small envelope.
Therefore, the particle must possess sufficient kinetic energy to
sustain the dissipation of the drag force and reach the perimeter
of the magnetic influence. The gravity force and settling velocity
for small particles is insignificant for the brief particle
transport period (typically <150 milliseconds) and in this model
are disregarded.
It is desirable to have a small a fluid pressure drop between the
separator inlet and lubricant outlet as possible. However, the
pressure drop is directly proportional to the flow rate of the
fluid and thus the tangential velocity of the circular flow. In
other words, as the pressure drop is reduced so too is the
tangential velocity of the fluid flow which drives the particles
from the cylindrical chamber into the collector exit passage. This
relationship limits the physical size (diameter) of the separator
and thus the amount of fluid flow there through. As a consequence,
enlarging the diameter of the separator chamber to accommodate a
greater fluid flow reduces the tangential force of the fluid
flowing through the chamber and the ability to separate out the
particles.
Therefore, it is desirable to improve the debris transport
efficiency of the separated particle from the chamber wall to the
debris collection site in order to provide a cyclonic fluid
separator that can efficiently operate at greater fluid flow
rates.
SUMMARY OF THE INVENTION
An apparatus for separating liquid and particles from a mixture has
a separation chamber with a cylindrical wall that extends about a
longitudinal axis between a first end wall and a second end wall.
An inlet for receiving the mixture opens into the separation
chamber tangentially to the cylindrical wall. A fluid outlet at the
second end of the separation chamber provides an exit for the
liquid to flow from the separation chamber. A debris passage opens
through the cylindrical wall and is oriented wherein a radial
velocity of the particles within the separation chamber directs the
particles through the debris passage. Preferably, the debris
passage extends radially from the longitudinal axis of the
separation chamber. The debris passage leads to a particle
collection chamber in which the particles accumulate. The
collection chamber preferably extends from the debris passage
parallel to the longitudinal axis and away from the first end of
the separation chamber.
Unlike prior separators that relied on the tangential velocity of
the particles, the present apparatus utilizes the greater radial
velocity to drive the particles from the separation chamber into
the particle collection chamber.
The present apparatus also can be use to separate gas, as well as
liquid and particles, from a mixture. In this embodiment, a gas
outlet is provided in the first end of the separation chamber
through which gas separated from the mixture exits.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a radial cross section view through a prior three-phase
cyclonic separator;
FIG. 2 is an axial cross-section through a three-phase cyclonic
separator according to the present invention;
FIG. 3 is a cross-section along line 2-2 in FIG. 2 depicting the
inlet of the separator; and
FIG. 4 is a cross-section along line 3-3 in FIG. 2 depicting the
debris outlet of the separator.
DETAILED DESCRIPTION OF THE INVENTION
With initial reference to FIG. 2, a three-phase separator 10 is
provided to separate liquid, gas and solid components from a
mixture. Although the separator 10 has particular utility in an
engine lubrication system, it should be appreciated that the
separator can be employed in other types of fluid systems. The
separator 10 comprises a housing 12 with a tubular, cylindrical
side wall 11 extending between a first end wall 16 and a second end
wall 26, thereby forming a circular cylindrical separation chamber
14 with a first, or top, end 15 and a second, or bottom, end 18.
The housing 12 abuts a lubricant reservoir 19 of the lubrication
system and is attached thereto by plurality of machine screws 17 or
other fastening mechanism.
With additional reference to FIG. 3, an inlet 20 opens into the
separation chamber 14 adjacent the first end wall 16 and is aligned
tangentially with curved surface of the cylindrical separation
chamber 14. As will be described, a mixture of materials to be
separated enters the separation chamber 14 through the inlet 20 and
thereafter flows in a helical vortex 22 that spirals downward
through the separation chamber toward the second end 18. A fluid
outlet 24 is formed through the second end wall 26 of the
separation chamber 14 with an annular collector wall 28 projecting
as a tube from the second end wall into the separation chamber 14
and surrounding the fluid outlet 24. Note that the fluid outlet 24
of the separator 10 is aligned with a central first longitudinal
axis 25 about which the separation chamber 14 is centered and that
axis extends into the lubricant reservoir 19.
Referring to FIGS. 2 and 4, the second end wall 26 and the annular
collector wall 28 form a barrier defining a collection region 30
within the separation chamber 14 which receives particles that have
been separated from the mixture entering through the inlet 20. A
debris passage 32 opens through the cylindrical side wall 11 of the
separation chamber 14 adjacent the collection region 30. The debris
passage 32 also opens into an elongated debris collection chamber
34 outside the separation chamber and having primary axis 35 that
extends parallel to the first longitudinal axis 25. Note that the
debris passage 32 is centered on a second longitudinal axis 33
extending radially from the first longitudinal axis 25 and is not
aligned tangentially with the curved inner surface 21 of the
separation chamber. Thus the debris passage 32 is orthogonal to the
primary axis of the debris collection chamber 34. It will be
understood from the description of operation of the separator that
the debris passage 32 does not have to be precisely aligned with
the second longitudinal axis 33.
The debris passage 32 communicates with the upper section of the
particle collection chamber 34 which continues to extend downward
away from the first end 15 of the separation chamber and toward the
lubricant reservoir 19. A plug 36 closes an external opening 37 at
the lower end of the particle collection chamber 34 and is
removable when it is necessary to clean out the particles that are
collected.
A conventional magnetic probe 38, for gathering metal particles
that enter the particle collection chamber 34, is located in an
aperture that opens into that chamber adjacent the plug 36. The
magnetic probe produces an electrical signal that indicates the
amount of metal particles that have been gathered. When the
electrical signal indicates that a large quantity of particle have
been gathered, the magnetic probe 38 can be removed to extract
particles and clean the probe. A debris sensor 40 of a flow-through
type is located along the particle collection chamber 34 between
the debris passage 32 and the magnetic probe 38. The debris sensor
40 produces an electrical signal indicating that the amount of
particles passing through the particle collection chamber from the
debris passage 32 to the plug 36. For example, the debris sensor 40
can be a conventional optical device that transmits a beam of light
across the particle collection chamber 34 to a light detector that
responds by producing a second electrical signal. The intensity of
the light that reaches the detector is affected by the debris
passing through the particle collection chamber. Other types of
sensors, such as an ultrasonic device, can also be utilized to
detect the flow of particles through the particle collection
chamber.
The separator 10 includes a gas outlet 46 in the center of the
first end wall 16 within the separation chamber 14. The gas
separated from the mixture entering the separation chamber 14 and
also gas within the lubricant reservoir 19 are vented through the
gas outlet 46. A pressure relief valve 48 is attached to the gas
outlet 46 and opens a passage from the gas outlet when the pressure
within the separator 10 reaches a given threshold level, (e.g.
0.5-0.7 bar).
INDUSTRIAL APPLICABILITY
With reference to FIGS. 2 and 3, the present three-phase separator
10 has particular application to processing a lubricant for an
aircraft engine. Scavenger pumps feed the lubricant mixture under
the pressure from the engine into the inlet 20. The flow of the
lubricant mixture enters the separation chamber 14 tangentially to
the surface of the curved side wall 11 and follows a path curving
around the cylindrical interior surface of the separation chamber
14 and downward toward the second end wall 26 of the chamber
creating a helical vortex 22. The annular collector wall 28 divides
the separation chamber 14 into two concentric regions, a
cylindrical inner region 50 and an annular outer region 52 around
the inner region 50. The boundary between the inner and outer
regions 50 and 52 is indicated by dotted lines 53 in FIG. 2.
As the mixture spirals downward along the curved side wall 11 of
the housing 12, the cyclonic flow creates a centrifugal force that
drives the relatively heavy debris particles to the outer periphery
of the flow pattern, while at the same time allowing gas bubbles to
coalesce at the center of the pattern (about the central first
longitudinal axis 25). The debris particles are forced downward
into the outer annular collection region 30 where the second end
wall 26 arrests the downward motion of those particles.
Conventional cyclonic separators with a tangential debris exit
passage relied solely on the tangential component of the particle's
velocity and did not utilize the radial velocity component. In
those separators, the radial component of the particle velocity
occurred only during the separation process, i.e. as the particle
was centrifuged toward the curved side wall of the separation
chamber. Once at the wall, the radial component was arrested. A
centrifugal force still acted on the particle--but at this point
was detrimental to the direction of transport, i.e. the centrifugal
force pressed the particle against the sidewall.
The present three-phase separator 10 harnesses both velocity
components or at least the radial component which has the higher
velocity potential. In FIG. 4, a particle 42 at the opening of the
debris passage 32 has a velocity that can be resolved into
tangential velocity 44 and a radial velocity 46 depicted by
orthogonally oriented arrows. A simple equation defining particle
settling time in a gravity field is:
.times..function..rho..rho..times..times. ##EQU00003##
In a cyclonic separator, the value for "g.sub.s" in this equation
is much greater than one earth g. For example, a recent test on an
aircraft produced acceleration level of 50 g with tangential
velocity of 14 feet per second (FPS) at the flight idle speed of
the engine and 500 g with tangential velocity of 45 FPS at the
takeoff speed of the engine. The corresponding radial velocity
components were 21 FPS at flight idle speed and 210 FPS at takeoff
speed. This empirical data clearly demonstrates that the radial
particle velocity vector is significantly greater than the
tangential velocity vector.
Therefore, the debris passage 32 into the collection chamber 34 are
located in the present three-phase separator 10 at a position which
is not tangential to the curvature of the separation chamber side
wall 11. In fact, the debris passage 32 is aligned with a second
longitudinal axis 33 extending radially from the first longitudinal
axis 25 of the separation chamber 14 so as to take optimum
advantage of the radial particle velocity. However, the debris
passage 32 does not have to be precisely centered on the a line
extending radially from the first longitudinal axis 25 in order for
the radial velocity to force the particle through that passage.
Furthermore, the trailing vertical edge 49 of the debris passage 32
preferably is beveled to permit the tangential velocity to aid in
directing the particle into the collection chamber 34, however the
primary force for that motion still is the radial velocity.
Because the present invention utilizes the radial particle velocity
to drive particles from the separation chamber 14 and into the
debris passage 32, it functions more efficiently at lower fluid
flow rates, at which the particle velocity also is reduced, than a
conventional separator with a tangential debris exit passage. This
enables the hydraulic system to be designed to operate with a
smaller pressure drop across the present separator 10.
After entering the collection chamber 34, a debris particle travels
parallel to the first longitudinal axis 25 toward the opening 37 at
the remote end from the debris passage 32. Both magnetic and
non-magnetic particles are detected by the flow-through type debris
sensor 40 which emits a first electrical signal indicating that
debris. The magnetic probe 38 then gathers the metal particles in
that debris and emits a second electrical signal which indicates
the accumulated amount of metal particles. The first and second
electrical signals are applied to a computer for analysis of engine
wear. In addition, when those electrical signals indicate a
significant amount of debris has entered the collection chamber 34,
a technician removes the plug 36 and cleans out that chamber.
Returning to activity in the separation chamber 14, the cyclonic
fluid flow results in liquid from the lubricant mixture filling the
annular outer region 52 and the outer periphery of the inner region
50. The liquid spiraling downward exits through the fluid outlet 24
flowing into the lubricant reservoir 19. Any gas that is entrained
in this spiraling mixture migrates toward the first longitudinal
axis 25. The separated gas is able to flow downward through the
fluid outlet 24 into a vapor space at the top of the lubricant
reservoir 19. When pressure in that vapor space and the separation
chamber 14 increases above a predefined threshold (e.g. 0.5-0.7
bar), the pressure relief valve 48 opens allowing the gas to exit
via the outlet 46 at the top of the separation chamber.
The foregoing description was primarily directed to a preferred
embodiment of the invention. Although some attention was given to
various alternatives within the scope of the invention, it is
anticipated that one skilled in the art will likely realize
additional alternatives that are now apparent from disclosure of
embodiments of the invention. Accordingly, the scope of the
invention should be determined from the following claims and not
limited by the above disclosure.
* * * * *